have you guys ever heard of HP Lovecrafts short story titled 'The Haunter in The Dark'?

Basically, the plot is that the main character goes looking through an old abandoned church and find a artifact called The Shining Trapozohedron. Like all foolish mortals in Lovecrafts fiction he ends up using this artifact, not knowing what it does, and ends up summoning a monster that is hunting him but can only exist in complete and utter darkness. I don't want to spoil anything else about the story, but a cursed item like this would be fun to use on the players.

"The minds of gods are not for ponies to know or to judge. Accept that Sheila has a place for all of us in her grand plan, and be happy in the part you have to play."